Concrete Technology and Design of Concrete Structures Multiple Choice Questions and Answers

1. To determine the modulus of rupture, the size of test specimen used is
a) 150 x150 x500 mm
b) 100 x100 x700 mm
c) 150 x150 x700 mm
d) 100 x100 x500 mm

Ans: c

2. The property of fresh concrete, in which the water in the mix tends to rise to the surface while placing and compacting, is called
a) segregation
b) bleeding
c) bulking
d) creep

Ans: b

3. Select the incorrect statement
a) Lean mixes bleed more as compared to rich ones.
b) Bleeding can be minimized by adding pozzuolana finer aggregate.
c) Bleeding can be increased by addition 'of calcium chloride.
d) none of the above

Ans: d

4. The property of the ingredients to separate from each other while placing the concrete is called
a) segregation
b) compaction
c) shrinkage
d) bulking

Ans: a

5. Workability of concrete is directly proportional to
a) aggregate cement ratio
b) time of transit
c) grading of the aggregate
d) all of above
Ans: c

6. Workability of concrete is inversely pro¬portional to
a) time of transit
b) 'vater-cement ratio
c) the air in the mix
d) size of aggregate
Ans: a

7. Approximate value of shrinkage strain in concrete, is
a) 0.003
b) 0.0003
c) 0.00003
d) 0.03
Ans: b

8.      Air entrainment in the concrete increases
a) workability
b) strength
c) the effects of temperature variations
d) the unit weight
Ans: a

9. The relation between modulus of rupture fcr, splitting strength fcs and direct tensile strength fcl is given by
a) tcr -rcs = tct
b) fcr>fcs>fc.
C)      fcr<fcs<fc>
d)      fc5>fcr>fC.
Ans: b

10. The approximate value of the ratio between direct tensile strength and flexural strength is
a) 0.33
b) 0.5
c) 0.75
d) 1.0
Ans: b

11. Strength of concrete increases with
a) increase in water-cement ratio
b) increase in fineness of cement
c) decrease in curing time
d) decrease in size of aggregate
Ans: b

12. The relation between modulus of rupturefcr and characteristic strength of concrete fck is given by
a) fcr=0.35Vf7
b) fcr=0.57f7
c) fcr=0.7Vf7
d) fcr=1.2Vf7
where fcr and fck are in N/mm2'
Ans: c

13. The compressive strength of 100 mm cube as compared to 150 mm cube is always
a) less
b) more
c) equal
d) none of the above
Ans: b

14. According to IS : 456 -1978, the modulus of elasticity of concrete Ec (in N/mm2) can be taken as
a) Ec = = 5700
b) Ec = = 570
c) Ec = = 5700fck
d)    Ec = where fck N/mm2 = 700 is the characteristic strength in
Ans: a

15.    Increase in the moisture content in con-crete
a) reduces the strength
b) increases the strength
c) does not change the strength
d) all of the above
Ans: a

16. As compared to ordinary portland cement, use of pozzuolanic cement
a) reduces workability
b) increases bleeding
c) increases shrinkage
d) increases strength
Ans: c

17. Admixtures which cause early setting, and hardening of concrete are called
a) workability admixtures
b) accelerators
c) retarders
d) air entraining agents
Ans: b

18. The most commonly used admixture which prolongs the setting and hardening time is
a) gypsum
b) calcium chloride
c) sodium silicate
d) all of the above
Ans: a

19. The percentage of voids in cement is approximately
a) 25%
b) 40%
c) 60%
d) 80%
Ans: b

20. The strength of concrete after one year as compared to 28 days strength is about
a) 10 to 15% more
b) 15 to 20% more
c) 20 to 25% more
d) 25 to 50% more
Ans: c

Read More Questions:
Concrete Technology and Design MCQs Part1
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